A frequency setting unit for a radio telecommunications network comprising a first, reference base station transmitting signals at a first frequency, and a second base station transmitting at a second frequency; the frequency control unit comprising: a radio receiver for receiving signals from the first base station; analysis apparatus for analysing the received signals to determine the first frequency; and feedback apparatus responsive to the decoding apparatus and coupled to the second base station for adjusting the second frequency with the aim of establishing a desired relationship between the second frequency and the first frequency.